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Because process piping is frequently oversized for the needed flow range, a correctly sized valve will frequently have a smaller valve body size than the line size. Since the purpose of a control valve is to use up or take out energy in the flow stream (create a pressure drop), using a...

Hasseli, I suspect that JDPS2 works for Siemens because he writes, "we'll get this resolved immediately". We = Siemens At one time or another, all of us have run into the unfortunate situation of the blame game - finger pointing at another party, but you now have the manufacturer's...

Thanks for the update.

I've never had to use a bubble pot but it appears to be a condensate pot with a valve for releasing/purging collected air/gas/vapor at an elevated high point. I'm not quite sure why any collected gas will not create head pressure errors at the DP transmitter, like when an automobile's hydraulic...

You are aware that there are commercial chips that do the heavy lifting of analog and FSK signal processing. It's the specfication documents that tell all about the protocol details. The current HART 7 specifications are for sale on the HART foundation web site. The HART protocol has...

I don't even have a copy of that software, but I suspect that the level of support is typical of freeware, i.e. emailing the listed contact under help > about with an explanation of the symptoms to see if an update might fix it.

The non-periodic nature of the drop-outs is like what the industry experienced 30 years ago when a tech with a walkie-talkie portable radio stood next to, or in close vicinity of, a field transmitter. When the tech keyed the radio 'on' to transmit, an indicating transmitter would go wild...

The documentation for a free Modbus slave stack (for the AT91SAM ARM-based Flash MCU) http://www.atmel.com/Images/doc11098.pdf uses Lamesoft Modbus Doctor as an example of using a Modbus master/client to access the slave. The document has two screen shots of Modbus Doctor. The screen shot...

>Also how about the question when the alarm of transmitter triggers? I don't have a clue what temperature alarms your DCS triggers. I'm a temperature guy. Let me summarize what the situation appears to be at this point. 4 indicated temperature signals fault, drop out at the same...

The FC-11 4-20 mA Isolated Signal Conditioner (at the link provided) will work in this situation. I agree with Mr. Mostia, it's good practice to always use isolated inputs. It also pays to use temperature transmitters that are isolated. Lots of vendors have similar offerings. I...

You might want to check and confirm that the transmitter is not square rooting the signal AND the DCS is also square rooting the transmitter's square root signal. It's been known to happen more than once.

Adding the additional 4-20mA signal exceeded the common mode rejection ability of the analog input card. You've created a ground loop by adding a signal whose reference ground is at a different potential than the original signals. A mild ground loop appears as an offset or noise. A...

It isn't clear whether only one of 8 points has the drop out problem, or all eight. If all 8 there's some common mode failure associated with all 8. I'll assume that there was only one point going bad, and the replacement transmitter is using the same DC power supply, wiring and receiver...

> Alternatively, Have you seen problems with cables in the past? Yes, corrosion in pH cabling can be a problem. Increased resistance will definitely affect a relatively low voltage high impedance pH signal. It's one reason for using a pH transmitter, but corrosion problems on the...

> can I connect the 4 wires from each RS-485 Modbus slave device in parallel > and then send it to Modbus Master RS-485 (DCS)? Parallel? Yes, but it depends on whether the RS-485 connection on the DCS side is 4 wire or 2 wire. If it is 2 wire on the DCS end, then you convert the 4 wire...

Welcome to Control.com Substitution with a known good probe and running a cal check is a good troubleshooting technique for checking the analyzer. You did not mention what pH value you read when you connected the pH probe to the 2nd analyzer, only that it was "acceptable". Given that a...

It seems that the statement below is the governing rule for how the SHJ S6889 serial server operates: "If the device ID not match local address or 255,then S6889 will reorganize the data according to modbus protocol, send out through zigbee or RS485 port. If register 7 is 6889, then...

A colleague calls them - Mules (packs the bits and carries them) - Rules (protocol, who talks, who listens, error handling) and - Tools (application level that deals with the data)

1) >CRC The Modbus over serial line V1.02 spec says the RTU frame has the CRC low byte first, then the high byte. (page 13) Lammertbies calculates B56F for 01030442c80000 in CRC-16 too. http://www.lammertbies.nl/comm/info/crc-calculation.html For B56F, which is low, which is high...

Assuming they all talk Modbus RTU (or all talk Modbus ASCII), yes. Usually a single USB-to-RS485 converter is used on a master, like a PC. Multiple slaves on one network is called multidrop. It is usually wired (+) to (+) to (+) , (-) to (-) to (-), or A to A to A, B to B to B...